1. Field of the Invention
Recreational skiing has been on the increase over the years to the point where ski areas must make snow to supplement natural snow, because in many areas of the world not enough natural snow falls to satisfy the demand for good skiing conditions. Artificial snow, as it is sometimes called, is made in large quantities at many ski areas. Large amounts of energy is used in supplying the snow making guns; both water pumped at relatively high pressure, and compressed air is used. In consideration of the large amounts of energy consumed by the pumps and air compressors, or by the large electric motors which run the snow making machines of the fan type, it is important to increase the efficiency of snow making and reduce the energy required to make an amount of snow, and therefore, effectively reducing the cost of snow making.
2. Description of the Prior Art
It has been found that water droplets freeze into snow crystals more quickly, and at a slightly higher temperature if each droplet has a small particle of material such as dust to act as a nucleus to freeze around. In recent years, materials such as bacteria or yeast, various sugars, wood powders and silica particles for example, have been used for providing a nucleus for snow crystals to grow around. For health reasons some individuals have been concerned about the use of bacteria or yeast as a nucleating agent, which is sprayed into the atmosphere at a ski area. Ordinary cellulose, in the form of wood powder is hard to obtain in a particle size of uniform value in the range of 1 to 15 microns, which is a useful size for the use of snow making. Milled wood, or other types of cellulose, such as wheat stalks, have many unorganized particles which may cause some snow making equipment to clog up from accumulated deposits of the more coarse sized particles. Silica particles are in use at some ski areas, but some concern has been voiced about this substance possibly causing, through long enough exposure, abrasive wear to the snow making equipment which is in intimate contact with this particular nucleating material.
A product with the technical name of "Microcrystalline Cellulose" made by the FMC Corp. is a material made by removing the amorphous parts of the cellulose structure using a chemical process which leaves a more uniform crystal-like material quite unlike that made by milling whole cellulose such as wood fiber to small sized particles. A characteristic of microcrystalline cellulose which clearly distinguishes it from wood fiber types of cellulose is the specific gravity. According to the "Handbook of Chemistry and Physics", the average hardwood has a specific gravity of approximately 0.65 grams per cubic centimeter, while "microcrystalline cellulose" has a specific gravity of approximately 1.5 grams per cubic centimeter.